GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION - Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Condensed Statement of Income Captions [Line Items]
Net Income	$ 7,024	$ 48,830	$ 20,303	$ 9,084	$ 52,709	$ 70,958	$ 76,157	$ 132,751
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	2,457	2,459	2,460	4,177	4,182	3,997	7,376	12,356
Net unrealized loss	(261)	(264)		0			(525)	0	$ 0
Other Comprehensive Income	2,196			4,177			6,851	12,356
Comprehensive Income	9,220	$ 51,025	$ 22,763	13,261	$ 56,891	$ 74,955	83,008	145,107
Less: Comprehensive Income Attributable to Noncontrolling Interest	2,681			3,346			14,097	19,444
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	6,539			9,915			68,911	125,663
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income	(15,876)			(19,242)			(115,102)	(160,079)
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	5			2			11	6
Net unrealized loss	0						0
Other Comprehensive Income	5			2			11	6
Comprehensive Income	(15,871)			(19,240)			(115,091)	(160,073)
Less: Comprehensive Income Attributable to Noncontrolling Interest	2,681			3,346			14,097	19,444
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(18,552)			(22,586)			(129,188)	(179,517)
Parent Issuer | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	4,340			5,734			62,055	113,304
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	2,457			4,177			7,376	12,356
Net unrealized loss	(261)						(525)
Other Comprehensive Income	2,196			4,177			6,851	12,356
Comprehensive Income	6,536			9,911			68,906	125,660
Less: Comprehensive Income Attributable to Noncontrolling Interest	0			0			0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	6,536			9,911			68,906	125,660
Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	2,252			14,619			65,122	131,788
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	0			0			0
Net unrealized loss	0						0
Other Comprehensive Income	0			0			0	0
Comprehensive Income	2,252			14,619			65,122	131,788
Less: Comprehensive Income Attributable to Noncontrolling Interest	0			0			0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	2,252			14,619			65,122	131,788
Non-Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	9,338			(672)			27,505	(2,240)
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	0			0			0	0
Net unrealized loss	0						0
Other Comprehensive Income	0			0			0	0
Comprehensive Income	9,338			(672)			27,505	(2,240)
Less: Comprehensive Income Attributable to Noncontrolling Interest	0			0			0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	9,338			(672)			27,505	(2,240)
Non-Guarantor | Reportable Legal Entities | CCR Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income	6,970			8,645			36,577	49,978
Other Comprehensive Income (Loss):
Net Actuarial Gain (Loss)	(5)			(2)			(11)	(6)
Net unrealized loss	0						0
Other Comprehensive Income	(5)			(2)			(11)	(6)
Comprehensive Income	6,965			8,643			36,566	49,972
Less: Comprehensive Income Attributable to Noncontrolling Interest	0			0			0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	$ 6,965			$ 8,643			$ 36,566	$ 49,972